net: sock: introduce sock_queue_rcv_skb_reason()

In order to report the reasons of skb drops in 'sock_queue_rcv_skb()',
introduce the function 'sock_queue_rcv_skb_reason()'.

As the return value of 'sock_queue_rcv_skb()' is used as the error code,
we can't make it as drop reason and have to pass extra output argument.
'sock_queue_rcv_skb()' is used in many places, so we can't change it
directly.

Introduce the new function 'sock_queue_rcv_skb_reason()' and make
'sock_queue_rcv_skb()' an inline call to it.

Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>